In game history, the number of moves shown for each game is literally the total number of moves - White's and Black's. Please could this be changed so as to observe the normal convention that the number of moves in a game is the number made by White?

You can just divide by two... I really see no problem in that, although it is easier to spot early resigners the way you are asking. Early resigners = people who lower their rating for the daily warzone or before anykind of warzones.

I do not really know the reason, maybe the admins prefer to show the number of all moves in total instead of just the number of moves done by white, since you cannot know if black has done the same amount of moves or less.

The way it is now it is easier to spot who the winner is, or at least who the player who has done the last move is. Even black odd white.

I am still not too sure if that is the reason or not though. Maybe it was asked to make it that way to see the total moves done instead of the moves done by each player.